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A team of Canadian university researchers believes mine tailings could be reprocessed to trap greenhouse gas, creating both a source of revenue for mine operators and a method for the energy-intensive industry to offset the carbon dioxide emissions it generates.

Only about one per cent of the material unearthed in most mining operations is usable; the rest is discarded as waste.

But researchers say waste carbon dioxide could be chemically affixed to the other 99 per cent, in situations where the tailings are rich in magnesium silicate — which has an “inherent ability” to react to CO2 and transform into magnesium carbonate.

That means major CO2 sources such as Alberta’s oilsands, or B.C.’s northeast gas patch, could capture and pipe CO2 to mines where it would be sequestered in tailings rock.

The capacity for “CO2 fixation” could be five to 10 times as great as total greenhouse gas emissions for some mines, say the researchers, who are funded through a series of grants from Carbon Management Canada.

Magnesium silicate is common at many, but not all, mines. You won’t find it at coal mines, for example, but you’re likely to find it in deposits of copper, nickel, diamond, chromite, platinum, palladium, talc and asbestos.

The technology appears to be simpler and less risky than sequestering CO2 in retired underground gas wells, but it requires more research, said project member Michel Hitch, a mining engineer who teaches at the University of B.C.

Other members of the team are Greg Dipple and Ulrich Mayer of UBC’s earth, ocean and atmospheric sciences department, and Gordon Southam, who is at the University of Queensland.

Hitch noted that the fixation process is well-known in nature, but researchers are looking for a way to accelerate and scale it to keep pace with production at a modern mine mill.

As well, they need to develop a method to quantify the amount of CO2 that’s being sequestered.

“We have a process that takes place in nature, by (rock) just sitting there. Atlin Flats (in northwestern B.C.) are a great example,” Hitch said.

“It happens at really slow rates, tens of years, but we know it happens. We have come up with a way of accelerating that reaction.”

Hitch is using the rock grinding machine at UBC’s mining lab to look at methods of economically adding in CO2 during routine milling operations such as those that would occur at a copper mine.

Some large mines could sequester five million tonnes of CO2 per year — roughly four times as much carbon dioxide as the single-largest emission source in B.C. produces annually.

Hitch has already published four papers on the topic.

A mine getting paid to sequester carbon could operate with lower-grade ore than a more conventional mine — perhaps 20-per-cent lower grade, he said. That means lower-margin mines, which are typical for B.C.’s geology, could be more competitive internationally.

“You actually treat it like a byproduct credit. It’s like having a copper-gold mine where the gold is a byproduct or an accessory commodity.

“Not only do you get the CO2 credit but you also get the industrial product at the end of the line. You can use that material that has been chemically altered for all sorts of other purposes, for instance making cement, food additives, all sorts of things.”

Magnesium silicate is so common in rock formations, he added, that miners “would never run out of material.”

“Arguably … one day we would be mining for the purpose of sequestering CO2 and then we’d have nickel or some other commodity as the byproduct to the CO2. Wouldn’t that be bizarre?”

Carbon Management Canada is funded primarily by the federal and Alberta governments with contributions from industry.

Managing director Richard Adamson noted that one of the priorities is finding economical ways to deal with emissions.

“There has to be something done about the economics. We can’t just come up with technical solutions that cost hundreds of dollars per tonne of CO2. So in addition to solving the technical problems we have to solve the problems around reducing the cost (of sequestration) or generating byproducts that have value,” Adamson said.

Meanwhile, an international organization focused on CO2 storage announced Thursday that it has completed work on what it’s calling the world’s first guidelines for storing carbon dioxide underground.

Carmen Dybwad, CEO of the Regina-based International Performance Assessment Centre for Geological Storage of Carbon Dioxide, said the guidelines will be submitted to the International Standards Organization, or ISO, by year’s end.

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